Auckland water services company Watercare and the Ghella-Abergeldie Joint Venture have signed a contract for Watercare’s Central Interceptor, a $1.2bn wastewater tunnel with associated infrastructure.
Construction will begin with site works in August 2019 and the project is expected to be completed by 2025.
The 13km tunnel is part of Watercare’s wider wastewater strategy to protect and enhance the natural environment.
Watercare CEO Raveen Jaduram said that in older parts of central Auckland, wastewater and stormwater flow into a combined network of pipes and when it rains, stormwater overwhelms these pipes, which are designed to overflow into waterways.
He said: “We want everyone to be able to enjoy clean waterways, beaches and estuaries – that’s why we’re building the Central Interceptor.
“It will run underground from Western Springs to the Māngere Wastewater Treatment, collecting wastewater along the way via link sewers and drop shafts.”
The company said that it will also deliver projects such as separating the stormwater and wastewater pipes in the area while the Central Interceptor is being built.
The largest of these projects is the Grey Lynn wastewater tunnel, which is a 2km extension of the Central Interceptor.
Jaduram said: “We are delighted to announce that the Grey Lynn wastewater tunnel has been included in our construction contract with Ghella Abergeldie Joint Venture.
“This is an extremely good outcome for Aucklanders because it means a better result for the environment without any extra cost for customers.
“Together, the Central Interceptor and our western isthmus projects will reduce overflows in the area by at least 80 per cent.”
Recently, the company has built a large wastewater tunnel that runs from Parnell to Ōrākei, referred to as Project Hobson, using the tunnel-boring technique that will be employed for the Central Interceptor.
According to Jaduram, the Central Interceptor is the company’s largest project to date.
The Central Interceptor project will be funded using revenue from its water and wastewater service charges, infrastructure growth charges and borrowings.
Image: Ghella-Abergeldie JV to deliver $1.2bn wastewater tunnel in New Zealand. Photo: Courtesy of GHELLA SpA.